Doxorubicin-loaded chitosan–silver nanocarrier elicits chemoresistance in liver cancer cells

Doxorubicin (Dox) remains a cornerstone chemotherapeutic for hepatocellular carcinoma (HCC), yet its efficacy is constrained by systemic toxicity and intrinsic chemoresistance. Nanocarrier systems are proposed to overcome these limitations. This study aimed to develop and evaluate a chitosan-silver nanoparticle (Cs-AgNPs) system as a Dox delivery vehicle in HepG2 cells. Cs-AgNPs+Dox nanoparticles were synthesized and characterized by FTIR, XRD, and SEM. Drug-loading efficiency, release kinetics, and cytotoxicity were assessed and compared with those of free Dox. The modulation of PI3K/AKT/mTOR, NF-κB, autophagy, and apoptosis pathways was investigated using RT-qPCR and Western blotting. The formulation produced spherical, stable nanoparticles with high encapsulation efficiency and sustained release. Unexpectedly, at sub-toxic concentrations (6.25-50 µg/mL), Cs-AgNPs+Dox exhibited significantly lower cytotoxicity than free Dox. Mechanistic studies revealed strong activation of the PI3K/AKT/mTOR and NF-κB signaling cascades, accompanied by upregulation of autophagy markers (LC3, Beclin1) and reduced Caspase-3 expression. These findings indicate that the nanocarrier itself induces a pro-survival, chemoresistant phenotype in HepG2 cells. Cs-AgNPs is not an inert carrier but an active biological modulator that can antagonize Dox-induced cytotoxicity by stimulating key survival and autophagy pathways. This work underscores the importance of assessing the intrinsic bioactivity of metallic polymer hybrid nanocarriers, as their inadvertent compromise of therapeutic efficacy is a concern. Future optimization should integrate pathway-specific inhibitors to mitigate nanocarrier-induced resistance.